For years, researchers in the growing field of behavioral finance -- an academic area that's the love child of a wild fling between psychology, economics, and finance -- have been identifying ways in which our brains are poorly wired for making good investment decisions. Among the big names in the field is University of California Berkeley's Terrance Odean, who once told U.S. News & World Report that he wants to "be like the dentist, and put myself out of business" by helping people be smarter investors.

Do financial advisors add value?"Yes, they do add value," Odean quickly shot back. "Good financial advisors encourage investors to follow good investment practices. Left to their own devices, investors don't do that."

For an expert in behavioral finance, helping clients follow good investment practices means keeping them from getting too swayed by their momentary urges and making "dramatic portfolio changes for emotional reasons." An example of what that looks like in practice was advisors "encouraging clients to not get out of the market completely" in 2008.

Boiled down very simply, Odean said that good advisors add value by "[injecting] common sense where it's needed."

What makes a financial advisor a good financial advisor?"Good advisors start you off with a good portfolio and discourage you from shooting yourself in the foot. ... Good advisors have an eye toward taxes; really good advisors will help you find low-fee funds."

For people with more money and/or more complex financial situations, there's even more that a good advisor should bring to the table. As Odean put it: "For wealthier investors specifically, it may make even more sense for advice when it comes to taxes, estate planning, etc."

As with other experts I talked to, one thing that Odean stressed that customers shouldn't focus on when looking for a good financial advisor is a promise to beat the S&P 500 (INDEX: ^GSPC) . Odean told me that's "just the wrong thing to look at" and went even further to say that "your advisor should not be trying to beat the market."

"A rule of thumb," he concluded, is that "if an advisor sells himself as 'With me you'll beat the market,' go with someone else."

What's the bestpay structure for clientsto pay their broker or advisor?"The problem is that, first of all, we're not going to come out of this with me saying there's a perfect fee structure."

With that in mind, Odean noted that a "commission-based model encourages trading." This is a big problem because, according to some of Odean's best-known research, investors who trade the most tend to have the worst returns. And Odean knows from experience that commission-based brokers generally aren't interested in working with you if you're not trading a lot. "Many, many years ago," he said, "before I was an academic, brokers would call me up and encourage me to trade and he would be frank that he wanted me to trade or he wouldn't want me as a client."

These days, "more advisory and broker firms are moving toward a fee structure that's a percentage of [assets under management]. ... Now the incentive is not encouraging more trading, but the problem is that it's a zero-sum game," Odean cautioned. "The advice may add value, but what goes in one pocket comes out of the other. If the broker charges you 1%, you earn 1% less every year."

"There is another model: by the hour. Most investors don't go for it, but we do this for all sorts of things -- attorneys, etc." This model, however, requires that investors actually write the advisor a check rather than having a fee quietly removed from their assets, and that's a big part of the reason investors often don't go for it. "People give up 1% of $1 million without complaining, but if you charge them $500 per hour to work on their account, they get upset."

As he stressed at first, it's tough to say that any of the pay schemes is "perfect," but regardless of which structure you use, the bottom line is that "you should always know how much you're paying."

Are financial advisors appropriate for everyone?While in theory it might be great for everyone to have a third party available to keep their behavioral foibles in check, Odean recognizes that in practice it may not be quite so simple.

For those who have more money, the value of an advisor goes up because "this starts to tie in more complex situations -- estate planning, taxes, etc." While those wealthy investors could likely learn the ins and outs to do it on their own, it may not be worth their time. Odean related it to his own tax preparation: "These days, I don't do my own taxes. Could I do it? Sure. But I don't have the time or interest. It's just not where I want to spend my time."

However, Odean pointed out that an advisor relationship may not be as ideal for investors with lower levels of wealth. "At what point does it make sense for the advisor? If you've got $50,000 and they're charging 1% per year, you're not going to be a highly valued client." What should these folks do instead? "There's a range of wealth at which if you know to hold low-cost, diversified index funds and not do anything crazy, then you probably don't need an advisor." Odean didn't mention any index funds specifically, but Vanguard's funds -- including the Vanguard S&P 500 ETF (NYS: VOO) , Vanguard MSCI Emerging Markets ETF (NYS: VWO) , and Vanguard Dividend Appreciation ETF (NYS: VIG) -- are often regarded as some of the best, most cost-efficient index trackers on the market.

But that doesn't mean that all investors with smaller portfolios should try to do it on their own. The value of a financial advisor largely lies in your "propensity for shooting yourself in the foot." If you're an investor who tends to get carried away by the emotions of the market, then a financial advisor may be a good bet no matter what your wealth level.

At the time this
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